Non-aqueous electrolyte batteries, which typically include lithium ion secondary batteries, have recently been and currently are finding practical applications as electrochemical devices showing a high energy density. Ordinary lithium ion secondary batteries have a positive electrode formed by using transition metal oxide as positive active material and a negative electrode formed by using carbon as negative active material and contains an electrolyte salt which is a lithium salt such as LiPF6 and a non-aqueous electrolyte which is a carbonate type organic solvent. However, intercalation/deintercalation of most lithium ions takes place at a potential level lower than the reduction decomposition potential of the non-aqueous solvent to the carbon material. Therefore, while lithium ion secondary batteries show a high energy density, they are accompanied by a problem of a short service life and poor operation characteristics at high temperature.
Proposals have been made to use a negative active material with which intercalation/deintercalation of lithium ions takes place at a potential level higher than the reduction decomposition potential of the non-aqueous solvent. According to these proposals, lithium titanate with which intercalation/deintercalation of lithium ions takes place at about 1.5 V is employed as the negative active material (refer to, e.g., Patent Document 1). Lithium ion batteries having a negative electrode of such a negative active material show an excellent service life and good operation characteristics at high temperature. Many papers have been published and many reports have been made at scientific conferences on non-aqueous electrolyte batteries using lithium titanate as negative active material and such non-aqueous electrolyte batteries have been commercialized (refer to, e.g., Non-Patent Document 1, coin-type lithium ion secondary battery (SONY) etc.). Additionally, the use of lithium titanate as negative active material in highly reliable capacitors has been discussed in recent years for the purpose of improving the energy density thereof.    Patent Document 1: JP-B-3502118    Non-Patent Document 1: Journal of Power Sources 146 (2005) 636-639
However, Non-aqueous electrolyte batteries employing lithium titanate as negative active material are accompanied by a problem of gas generation. This problem hardly occurs in coil batteries and cylindrical batteries having a very strong battery jar but can arise as swollen batteries in the case of flat type batteries and batteries using metal resin laminate film as sheath. A proposal has been made to suppress gas generation by optimizing the carbonic substance that is a conducting agent in order to dissolve this problem (refer to, e.g., Patent Document 2).    Patent Document 2: JP-A-2005-100770
Besides, proposals of admixing an active material that occludes lithium ions at a potential lower than that of lithium titanate as auxiliary negative active material have been made as anti-overdischarge/anti-overcharge measures of a lithium ion battery employing lithium titanate as negative active material (refer to, e.g., Patent Document 3).    Patent Document 3: JP-B-3269396
Furthermore, proposals of admixing amorphous carbon as auxiliary negative active material to improve the cycle characteristic of a lithium ion battery employing lithium titanate as negative active material have been made (refer to, e.g., Patent Document 4).    Patent Document 4: JP-A-2001-126727
Additionally, proposal of admixing lithium titanate as auxiliary negative active material as anti-overdischarge measures of a lithium ion battery employing a carbon material as negative active material have been made (refer to, e.g., Patent Document 5).    Patent Document 5: JP-A-2004-63394
Still additionally, the invention of “a non-aqueous electrolyte secondary battery characterized by comprising a housing member, a non-aqueous electrolyte contained in the housing member and containing chain sulfite, a positive electrode contained in the housing member and capable of occluding/releasing Li and a negative electrode contained in the housing member and containing a conducting agent containing a carbonic substance and lithium titanate” is known (refer to, e.g., Patent Document 6).
The Patent Document 6 describes that “this additive forms a fine and stable coat film on the surface of the negative electrode at a negative electrode potential of about 1.3 V, which stably exists within the normal voltage range of the non-aqueous electrolyte secondary battery thereafter.” and that “as a result of checking it by means of a surface analysis, the film coat was constituted by an inorganic film coat where Li2SO3 exists as principal ingredient and mixed with LiF and other ingredients and an organic film coat formed by ROsO2Li, ROCO2Li, R═CH3(CH)CH2 or R═CH2—CH2 and other ingredients.” (paragraphs 0031, 0033, 0114, 0123) and also describes that “a carbonic substance is employed as conducting agent for increasing conductivity and reducing the contact resistance with the collector. The additive to be employed for the purpose of the present invention can form a fine and stable film coat on the surface of the carbonic substance. The film coat has a strong effect of obstructing the reaction of the carbonic substance and the non-aqueous electrolyte and suppressing gas generation and shows an excellent hot cycle characteristic”. However, since the “carbonic substance” is a conducting agent and not an active material and hence its effect of suppressing gas generation is not satisfactory as evidenced by examples (Comparative Examples 2, 3) hereinafter and a non-aqueous electrolyte containing a specific additive of “chain sulfite” has to be used in order to form a film coat containing lithium ions of “Li2SO3”, “LiF” or the like.    Patent Document 6: JP-A-2005-317508
Patent Document 7 describes that “while no particular problem arises when a non-aqueous electrolyte secondary battery employing lithium titanate as negative active material is used as main power source of a portable appliance, there arises a problem of degraded battery characteristics when the non-aqueous electrolyte secondary battery is used as memory backup power source showing an operating voltage of about 3.0 V. The reason for this is that, when a non-aqueous electrolyte secondary battery as described above is used as main power source of a portable appliance, a film coat showing an excellent ion conductivity is formed on the surface of the negative electrode because the negative electrode is charged to about 0.1 V in reference to lithium metal and the film coat suppresses the reaction of the negative electrode, and prevents the decomposition of the non-aqueous electrolyte, or prevents to destroy and the negative electrode structurally. To the contrary, when a non-aqueous electrolyte secondary battery as described above is used as memory backup power source showing an operating voltage of about 3.0 V, the charging step is conducted with a minute electric current of about 1 to 5 μA, while maintaining a constant voltage condition of about 3.0 V for long period, and the negative electrode is charged only to about 0.8 V in reference to lithium metal so that no such a film coat is formed on the surface of the negative electrode and hence the negative electrode and the non-aqueous liquid electrolyte react with each other to decompose the non-aqueous liquid electrolyte and structurally destroy the negative electrode” (see paragraphs 0006 and 0007). However, the invention described in the Patent Document 7 is “a non-aqueous electrolyte secondary battery comprising a positive electrode and a negative electrode containing a negative active material of lithium titanate and a conducting agent and a non-aqueous electrolyte, characterized in that the conducting agent used in the negative electrode is vapor grown carbon fiber that is graphitized and showing a lattice constant C0 of not less than 6.7 Å and not more than 6.8 Å in the laminating direction as determined by X-ray diffraction.” (Claim 1) and “the conducting agent” of the negative electrode adapted to use lithium titanate as active material is modified on condition that “the secondary battery is charged with a minute electric current of about 1 to 5 μA, while maintaining a constant voltage condition of about 3.0 V for long period” (paragraph 0008) so that the Patent Document 7 does not suggest charging a non-aqueous electrolyte secondary battery comprising a negative electrode containing lithium titanate and some other auxiliary active material to about 0.1 V in reference to lithium metal.    Patent Document 7: JP-A-2005-317509